Method and apparatus for reducing tubing



July 12, 1966 A. J. SOFRANKO METHOD AND APPARATUS FOR REDUCING TUBING Filed April 9, 1963 4 Sheets-Sheet l INVENTOR.

4770E/VEY July 1966 A. J. SOFRANKO I METHOD AND APPARATUS FOR REDUCING TUBING Filed April 9, 1963 4 Sheets-Sheet 2 lllflllllllllllh\lllllllllllllll |||||||||||m|m INVENTOR.

l/VDAEW .J. SOFAJ/V/(O ATTORNEY July 12, 1966 A. J. SOFRANKO METHOD AND APPARATUS FOR REDUCING TUBING 4 Sheets-Sheet 5 Filed April 9, 1963 INVENTOR.

ANDREWJ SOFAA/VKO zrrae/vsv July 12, 1966 A. J. SOFRANKO METHOD AND APPARATUS FOR REDUCING TUBING 4 $heets$heet 4 Filed April 9, 1963 ad i \Qv mm INVENTOR. 14/1 0195 W J. SOFAA/VKO United States Patent 3,260,090 METHOD AND APPARATUS FOR REDUCING TUBING Andrew J. Sofranko, 40 E. 40th St., Reitfton, Reading, Pa. Filed Apr. 9, 1963, Ser. No. 271,710 13 Claims. (Cl. 72-126) This invention relates to a method and apparatus for reducing tubing and more particularly to a method and apparatus for reducing the diameter and/ or the wall thickness of tubing.

Many prior art tu-be reducing apparatus employ tapered work rolls in conjunction with a mandrel for reducing the diameter and wall thickness of tubing or only the tapered work rolls for reducing the diameter of tubing. In these apparatus, the work rolls may have a plain working surface or they may be provided with spiral working surfaces. Examples of tube reducing apparatus having these types of work rolls may be found in US. Patents Nos. 2,358,307, 2,384,457, 2,562,785 and 2,650,509.

These and other tube reducing apparatus have certain inherent disadvantages which are overcome by the present invention. For example, when plain tapered rolls are employed with or without the use of a mandrel, considerable force is required to overcome rolling pressure in order to advance the tube through the rolls. In this apparatus, the tube must be literally pushed through the work rolls. Further, since the work rolls are in line contact with the tubing the rolling force provided by each roll is spread along the entire length of the roll. Hence, the separating forces, i.e., the forcing tending to spread the work rolls apart, is relatively large. Consequently, the bearings which rotatably support the Work rolls must be large. Still further, as a tube is being reduced, the tube will also be elongated. As for example, a fifty percent reduction in the area of the tube will be accompanied by an elongation of approximately twice the original length. As the tube is being reduced, the reduced end of the tube will want to move longitudinally through the rolls. It should be evident then that when plain tapered Work rolls are used, the elongation of the tube is resisted since no space is provided through which the tube can move. Hence, the force created by the elongation of the tube serves only to increase the separating forces mentioned above.

When tape-red work rolls are used having a working surface which spirals continuously around the rolls, the same frictional rolling force must be overcome in order to advance the tube through the rolls.

The above described types of apparatus require the tube to be pushed through the rolls with considerable force. None of these apparatus provides a means by which the tube may be fed through the work rolls without overcoming the rolling pressure.

One disadvantage which is not evident concerns the relation of the rotational speed of the work roll with respect to the tube at all points along the taper of the tube. It is very desirable that the work roll walk or roll over the tube rather than skid over it. Since the diameter of the tube diminishes throughout the length of the taper, it should be evident that the rotational speed of the work roll must change in order for the work roll to walk or roll over the tube. This change of rotational speed has never been accomplished heretofore.

Accordingly, the primary objects of the present invention include:

To provide a novel tube reducing apparatus which may be used with equal utility in a cold work process or a hot work process;

To provide novel work rolls, each of which includes at least one spiral working surface which extends around the circumference of the work rolls through an arc of less journaled within the housing 3,260,090 Patented July 12, 1966 than 360 whereby only a small portion at a time of the tube is Worked;

To provide novel work rolls which have a break in the working surfaces through which the tube may be fed with a minimum of force;

To provide a tube reducing apparatus wherein the separating forces are at a minimum;

To provide a tube reducing apparatus having novel differential drive means;

To provide a novel tube reducing apparatus wherein there is no slippage between the spiral working surfaces of the work rolls and the tube surface;

To provide a tube reducing apparatus having novel feed mechanism for incrementally feeding the tube through the tube reducing apparatus; and

To provide a novel method for reducing tubing.

These and other objects and advantages of the present invention will become apparent from the following detailed description 'by reference to the accompanying drawings, in which:

FIGURE 1 is an elevation view, partly in cross-section, illustrating the preferred embodiment of the present invention;

FIG. 2 is a cross-sectional view, taken along the line 2-2 of FIG. 1;

FIG. 3 is a cross-sectional view, taken along the line 33 of FIG. 1, illustrating the relationship of the planetary gears of the work rolls with respect to a ring gear;

FIG. 4 is an elevation view schematically illustrating the preferred embodiment of the drive means;

FIG. 5 is a cross-sectional view, taken along the line 5-5 of FIG. 1, illustrating the contact of the work rolls with a tube being reduced;

FIG. 6 is a schematic illustration of the preferred embodiment of a work roll shown engaged on a tube and further showing the spiral working surface and its path over the tube;

FIG. 7 is a cross-sectional view, taken along the line 7-7 of FIG. 6;

FIG. 8 is a plan view of the tapered portion of a tube laid fiat and schematically illustrating the overlapping paths of the spiral working surfaces of the work rolls;

FIG. 9 is a schematic illustration, similar to FIG. 5, of an alternative embodiment of a work roll;

'FIG. 10 is a cross-sectional view, on an enlarged scale of the novel tube feeding mechanism of the present invention; and

FIGS. 11 and 12 are schematic illustrations of alternative embodiments of the drive means of the present invention.

According to the present invention, a tube reducing apparatus is provided having a housing supported for rotation about its central axis. Tapered work rolls are for rotation about their longitudinal axes. First drive means is provided for rotating the housing whereby the housing and the work rolls revolve as a unit about the central axis of the housing. Second drive means also is provided for rotating the work rolls in synchronism about their longitudinal axes.

Each of the tapered work rolls includes at least one spiral surface which extends along substantially the entire length of the tapered work roll. The spiral working surfaces extend around the circumference of the work roll through an arc of less than 360 whereby each work roll is provided with a break or low spot in the working surface. The break or low spot in the working surface serves as a means for feeding the tubing through the work rolls with a minimum of force.

The tapered work rolls are supported so that their longitudinal axes are parallel and equidistantly spaced from one another and the central axis of the housing. In this position the tapered work rolls present gradually converging working surfaces to the tube. The tube is fed centrally between the smaller diameter ends of the work rolls.

In the preferred embodiment of the present invention, the rotational speed of the work rolls about their longitudinal axes is varied whereby those portions of the working surfaces in contact with the tube remain stationary relative to the outer surface of the tube. That is to say, the rotational speed of the work rolls is controlled whereby the work rolls walk around the tube throughout the length of the taper in the tube. Hence, in the present invention the tube is not subject to work roll skidding which would mar the surface of the tube.

The present tube reducing apparatus also is provided with a novel tube feeding mechanism which automatically advances the tube through the work rolls only when the aforementioned breaks or low spots in the work rolls are adjacent to the tubing. Thus when each of the work rolls has only one spiral working surface, the tube is advanced at the end of each revolution of the work rolls.

Alternatively, each of the present work rolls may be provided with more than one spiral working surface. As for example, each work roll may be provided with two spiral working surfaces each of which extends along substantially the entire length of the work roll and around the circumference thereof through an arc of less than 180. In this case two breaks or low spots are provided in each roll so that the tube is advanced through the work rolls twice during each complete revolution of the work rolls.

The preferred embodiment of the present invention is illustrated in FIGS. 1 to 9. Referring in particular to FIGS. 1, 2, 3 and 4, there is illustrated a tube reducing apparatus generally indicated by the numeral 20. The tube reducing apparatus generally comprises a tube reducing section 22, a tube feeding section 24 and a drive section 26, all of which are supported on a base 28.

The tube reducing section 22 comprises a stationary frame within which a housing 31 is rotatably supported by means of bearings 32 for rotation about the central axis indicated by the dash-dot line 33. The housing 31 comprises a roll carrier frame 34 which is rotatably supported by the bearings 32 and a roll chock 35 positioned within the roll carrier frame 34 and rigidly secured thereto as at 36. Within the housing 31 are tapered work rolls 38 which are j'ournaled thereto for rotation about their longitudinal axes indicated by the dash-dot lines 40. Each of the tapered work rolls 38 has extension shafts 42, 44, one each projecting from each end thereof, which are rotatably supported in roll chock end walls 46, 48, respectively, by any suitable means such as bushings 50.

The present tube reducing apparatus 20 preferably employs three of the tapered work rolls 38, as can clearly be seen in FIG. 3. FIG. 1 is a modified cross-sectional view wherein only two of the tapered work rolls 38 are illustrated for the sake of clarity. As can best be seen by comparing FIGS. 1 and 3, the longitudinal axes 40 are parallel to one another and the central axis 33 and are equidistantly spaced from one another and the central axis 33.

Each of the tapered Work rolls 38 preferably includes one spiral working surface 52 which extends substantially along the entire length thereof and around the circumference thereof through an arc of less than 360. The incomplete extension of the working surface 52 around the circumference of the tapered work roll 38 provides each work roll 38 with a break or low spot 54 which serves as a means for advancing the tube being reduced between and through the work rolls 38.

As can best be seen in FIG. 1, a tube 56 is introduced through an entrance port 58 in the roll chock end wall 48 and then between the smaller diameter ends 60 of the tapered work rolls 38. The tube 56 is then advanced through the large diameter ends 62 of the tapered work rolls 38 and through an exit port 64 in the roll chock end wall 46. As the tube 56 advances, the action of the tapered work rolls 38 reduces the diameter and the wall thickness of the tube 56 and thus forms a taper 66 therein. Internally of the tube 56 and in the region of the taper 66, there is provided a mandrel 68 which supports the tube 56 while it is being reduced. The mandrel 68 is secured to the end of a mandrel support bar 69 and is maintained in a fixed position relative to the tapered work rolls 38 in a manner which will be described later in the specification. The mandrel 68 is used to control the wall thickness of and hence the inside diameter of the resulting reduced tube. It should be evident that this control may be exercised by a change in the-size of the mandrel 68. The present tube reducing apparatus 20 also may be used to reduce tubing without the aid of a mandrel. In this instance, however, the wall thickness will be increased.

The tube feeding section 24 generally comprises a tube carriage 70 which frictionally engages the tube 56 and which also is engaged in driving relation with a threaded drive shaft 72. The threaded drive shaft 72 is supported at its ends in bearing box 74. One end of the threaded drive shaft 72 preferably is connected by means of a drive chain 76 to a two-position clutch 78. The twoposition clutch 78 comprises a tube feed drive sprocket 80, a high speed carriage return sprocket 82, and a central connecting sprocket 84 shown engaged with the tube feed drive sprocket 86. The connecting sprocket 84 also is connected to a high speed return drive 86 which serves to rapidly return the tube carriage 70 to its start position.

The tube feeding section 24 also includes a mandrel positioning means 88 which comprises a mandrel retract cylinder 90, a mandrel support slide 92, and a support slide abutment 94. The mandrel support bar 69 is secured to the mandrel support slide 92 and extends therefrom to the mandrel retract cylinder 90. The mandrel retract cylinder preferably is fluid operated and includes a piston 96 which is slideably supported therein and which is connected to the mandrel support bar 69.

The mandrel support slide 92 is slideable along a guideway 98 which is contiguous with the base 28. As can be seen in FIG. 1, the mandrel support slide 92 is engaged with the support slide abutment 94. In this position, the mandrel 68 is properly positioned with respect to the tapered work rolls 38.

Referring to FIGS. 1 to 4, the driving section 26 has a main drive shaft 100 which is supported at spaced points along its length by means of bearing blocks 102.

Secured at one end of the main drive shaft 100 is the two-position clutch '78. Connected to the other end of the main drive shaft 100 is a main drive motor 104.

In order to rotate the housing 31 about its central axis 33, external housing gears 106 are provided at each end thereof. The external housing gears 106 mesh with housing drive gears 108 which are secured to the main drive shaft 100.

In order to rotate the tapered work rolls 38 about their longitudinal axes 40, each work roll 38 is provided with a planetary gear 110 secured to the extension shaft 42 and externally of the housing 31. The planetary gears 110 are connected for synchronous rotation by means of a ring gear 112 which is supported above the base 28 by means of a second stationary frame 114. The ring gear 112 has a hub portion 116 which is rotatably secured to the second stationary frame 114 by means of bearings 118. The hub portion 116 has a longitudinal opening 120 which is concentrically aligned with the central axis 33 and provides a passageway for the reduced tube 56. Secured to the end of the hub portion 116 is a drive gear 122.

A differential drive 124 is employed to connect the drive gear 122 of the ring gear 112 to -a first work roll drive gear 126 which is secured to the main drive shaft 100. The differential drive 124 includes a differential drive shaft 128 which has a first gear 130 secured at one end thereof and meshing with the drive gear 122 of the ring gear 112. The differential drive 124 includes a constant speed section 132 and a variable speed section 134. The constant speed section 132 is rotatably supported on the drive shaft 128 and is directly connected to the first work roll drive gear 126 by means of a second gear 136. The variable speed section 134 is also r-otatably supported on the differential drive shaft 128 and is connected to the hydraulic motor 138 by means of intermeshing gears 140, 1427 The differential drive 124 also includes a pair of miter gears 144 which are rotatably supported on stub shafts 146 which are secured to the differential drive shaft 128. The miter gears 144 are maintained in air meshing relation with drive miter gear 148 of the constant speed section 132 and a drive miter gear 150 of the variable speed section 134. The drive miter gear 148 is contiguous with the second gear 136 of the constant speed section 132 and the drive miter gear 150 is contiguous with the gear 142 of the variable speed section 134.

The hydraulic motor 138 is connected to a hydraulic pump 152 by means of a conduit 154. The conduit 154 serves to communicate a working fluid, such as oil, to the hydraulic motor 138. The conduit 155 communicates a Working fluid discharged from the hydraulic motor 138 to a sump 156. A conduit 157 serves to communicate the working fluid from the sump 156 to the hydraulic pump 152. The hydraulic pump 152 preferably is of .the variable delivery type so that the speed of the hydraulic motor 138 may be varied. In order to vary the speed of the hydraulic motor 138 the hydraulic pump 152 is provided with a servomechanism to vary its output. This servomechanism has been schematically illustrated as comprising a plunger 158 operable by means of an arm 160 riding on a cam 162. The cam 162 is contiguous with a first cam drive gear 164 which, in turn, meshes with a second cam drive gear 166 which is secured to the main drive shaft 100.

In operation then, the housing drive gears 108 rotate the housing 31 at a constant speed about the central axis 33. Simultaneously, the first work roll drive gear 126 rotates the constant speed section 132 of the differential drive 124 at a constant speed. The hydraulic motor 138, through the action of the differential drive 124, adds to or subtracts from the constant speed of the constant speed section 132. Hence, the rotational speed of the Work rolls 38 about their longitudinal axes 40 is varied from a predetermined minimum value to a predetermined maximum value. It should be evident, however, that the range of speeds as well as the change of speed with respect to time is a function of the contour of the cam 162.

As hereinbefore stated, it is preferable that the working surfaces 52 Walk or roll over the surface of the tubing. It should be evident then, that since the diameter of the tapered work roll 38 changes throughout the length thereof, the rotational speed of the tapered work roll 38 must also change. As can be seen in FIG. 6, the diameter of the tapered work roll 38 increases from the feed end to the discharge end. Consequently, during each revolution or cycle the tapered work roll 38 must be decelerated from a predetermined maximum speed to a predetermined minimum speed as the working surface 52 progresses from the small diameter end to the large diameter end; and thereafter must be accelerated to the predetermined maximum speed when the break or low spot 54 is adjacent to the tube 56. It should be evident then that the deceleration of the work roll 38 comprises a predominantly major portion of each revolution or cycle.

Referring now to FIGS. 5 and 6, the longitudinal axes 40 of the tapered Work rolls 38 are parallel and equidistantly spaced from one another and the central axis 33. As can be seen, each of the spiral working surfaces 52 is in point contact with the tube 56 as indicated at 168. The tapered work rolls 38 are rotated in synchronism whereby the point contacts 168 are disposed around the tube 56 on a common circumference thereof indicated by the dotted line 170 (see FIG. 6). As the tapered work rolls 38 are rotated in synchronism about their longitudinal axes 40 and revolved about the central axis 33, the point contacts 168 of each working surface 52 will describe a spiral path 171 as indicated in phantom outline in FIG. 6. Thus, the rolling forces provided by the tapered work rolls 38 through a set of point contacts 168 are displaced spirally around the tube 56 longitudinally thereof.

It should be understood at this time that the phrase point contact as used in the specification does not define a mathematical point but rather the small area of contact between the working surfaces 52 and the tube 56.

When the tapered work rolls 38 complete one revolution, the breaks or low spots 54 will be positioned adjacent to the tube 56. At this time, the tube 56 will be advanced a small increment through the tapered work rolls 38 by means of the tube feeding section 24.

Referring now to FIGS. 6 and 7, the spiral working surfaces 52 of each tapered work roll 38 comprises a projection 172 which preferably is rectangular in shape. If desired, the large diameter end 162 of each of the tapered work rolls 38 may be provided with a finishing surface 174 which also extends around the circumference of the tapered work rolls 38 through an arc of less than 360. The finishing surface 174 serves to smooth out or finish the outer surface of the reduced portion of the tube 56 as well as size the finished tube as it emerges from the work rolls 38. Furthermore, when a lightweight tubing is being reduced, the finishing surface 174 serves as a die from which the reduced portion of the tubing emerges. As the tubing elongates, it pushes out under the finishing surface 174.

In FIG. 8, the taper 66 of the tube 56 has been laid out flat in order to more clearly show the overlapping paths of the working surfaces 52. The taper 66 is shown divided into three sections. The common circumference at one work point along the taper 66 is illustrated and on which corresponding portions of the working surfaces 52, indicated by the rectangles numbered 52a, 52b and 52c, are engaged with thesurface of the taper 66. The rectangles 52a, 52b and 52c correspond to the point contacts 168 of FIG. 6. A comparison of FIGS. 5 and 8 will show that since the adjacent tapered work rolls 38 are spaced apart by an angle of 120, the rectangles 52, 52b and 52c would also be spaced apart by angles of 120 as illustrated. The spiral working surfaces 52 of the tapered work rolls 38 will walk over the surface of the taper 66 along overlapping paths 171a, 1715 and 1710 defined in part by the dotted lines. It will be noted that each of the rectangles 52a, 52b and 520 extends beyond the dotted lines of its corresponding path. The dotted lines indicate the centerline of the overlap of adjacent paths. The path 171a has been sectioned to clearly indicate that portion of the taper 66 which is worked by the corresponding working surface. It is preferable in the present invention, that the paths 171a, 1711; and 1710 overlap as indicated so that the entire surface of the tube 56 in the region of the taper 66 may be worked during each revolution of the tapered Work rolls about the central axis 33. It should be evident that the amount of overlap is directly proportional to the width of the working surfaces 52. The finishing surface 174 (see FIG. 6) of each tapered work roll 38 produces a smooth surface area 180 at the small diameter end of the taper 66. The smooth surface area 180 is free of all markings which might be produced by the working surfaces 52 and is of the desired size, i.e., the desired diameter for the reduced tube.

As hereinbefore stated, it is preferable that each of the tapered work rolls 38 be provided with one spiral working surface 52. Alternatively, each tapered work roll may be provided with more than one spiral working surface. Illustrated in FIG. 9 is a tapered work roll 182 having two spiral working surfaces 184. Each spiral working surface 184 extends along substantially the entire length of the tapered work roll 182 and around the circumference thereof through an arc of less than 180. Thus, two breaks or low spots are provided in the tapered work rolls 182 which are diametrically opposite each other. In this embodiment, the tube would be advanced twice during each revolution of the tapered work roll 182.

Reference is now directed to FIG. 10 wherein the tube carriage 70 of the tube feeding section 24 is illustrated in cross section and on an enlarged scale. The carriage 70 comprises a main body portion 188 having a cylindrical opening 190 which terminates in a conical opening 192. The tube 56 extends through the openings 190, 192 and is frictionally held therein by means of a wedge 194. A wedge locking device 196 is engaged with the wedge 194 to maintain it in wedging relation with the tube 56 and the conical opening 192. The carriage 70 also is provided with drive shaft receiving openings 198 for-med in end walls 200 thereof. The end walls 200 cooperate with sidewalls 202 (only one shown) to define a cavity or guideway 204. Residing within and guided by the cavity 204 is a nut 206 which is threaded onto the threaded driven shaft 72. The nut 206 is slideable with respect to the carriage 70 and serves as a connecting means for connecting the carriage 70 with the threaded shaft 72. The nut 206 is maintained in nonrotating relation with the threaded shaft 72 by engaging the sidewalls 204. Interposed between the nut 206 and the forward end wall 200 is a spring member 208.

In operation, the threaded shaft 72 continuously advances the nut 206 along the cavity 202. As the nut 206 advances, it compresses the spring member 208 until such time that the tube 56 is free to advance whereupon the spring member 208 will advance the carriage 70 and the tube 56. Notice that the nut 206 is continuously advancing while the tube 56 advances in increments. The advance of the tube 56 occurs only when the breaks or low spots 54 in the tapered work rolls 38 are adjacent to the tube 56.

Alternative embodiments of the driving section are schematically illustrated in FIGS. 11 and 12. Corresponding numerals will be employed to identify corresponding parts already described.

In the embodiment illustrated in FIG. 11, the hydraulic motor 138 is connected directly to the first gear 130 which meshes with the drive gear 122 of the ring gear 112. As in the preferred embodiment of FIG. 4, the hydraulic pump 15-2 is connected to the hydraulic motor 138 by means of conduit 154. Conduit 155 serves to return the working fluid from the hydraulic motor 138 to the sump 156; and conduit 157 serves to convey the working fluid from the sump 156 to the hydraulic pump 152.

In this embodiment, however, a cam 210, of the eccentric type, is connected to the first cam drive gear 164. The plunger 158 is engaged with the periphery of the cam 210 and is thereby moved inwardly and outwardly of the hydraulic pump 152 in order to vary its rate of delivery to the hydraulic motor 138.

Hence, the main drive shaft 100 is rotated by the motor 104, gears 108 meshing with the external housing gears 106 will rotate the housing 31 (not shown) and the tapered work rolls 38 about the central axis 33. Simultaneously, the cam drive gears 166, 164 will rotate the cam 210. The hydraulic motor 138 thus will vary the rotational speed of the tapered work rolls 38 about their longitudinal axes 40 from a predetermined maximum speed so that they walk or roll over the tube throughthe predetermined maximum speed as hereinbefore described.

In the embodiment illustrated in FIG. 12, the ring gear 112 is freely rotatable on the bearings 118. The tapered Work rolls 38 also are freely rotatable so that as the housing 31 (not shown) is revolved about the central axis 33, the tapered work rolls 38 will seek the required speed so that they walk or roll over the tube throughout the length of the taper.

It should be noted at this time, that it is preferable in the present apparatus to have the spiral working surfaces walk or roll over the tubing throughout the length of the taper in the tube so as to produce a reduced tube having a smooth surface. Occasionally, however, the rough surface produced by the skidding of the spiral working surfaces is not objectionable as in the case where the reduced tubing will undergo further reduction in other sizes of the present tube reducing apparatus. In this case the embodiments of the driving section illustrated in FIGS. 4 and 11 may be easily modified to rotate the work rolls at a constant speed rather than at a variable speed.

In FIG. 4, for example, a disc having a fiat surface may be substituted for the cam 162. The speed at which the hydraulic motor 138 will run will be dependent on the width of the disc.

In FIG. 11, a disc having a center of rotation which is concentric with the cam drive gear 162 may be substituted for the cam 210. In this case the speed at which the hydraulic motor 138 will run will be dependent upon the diameter of the disc.

Although the invention has been shown in connection with certain specific embodiments, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention. In this respect it should be obvious that the embodiments of the driving section illustrated in FIGS. 4 and 11 could easily be modified so that the work rolls would be rotated at a constant speed while the rotational speed of the housing is varied to accomplish the desired results.

I claim as my invention:

1. A process for reducing tubing or the like comprising the steps of passing the tube centrally between a plurality of tapered work rolls each having a spiral working surface extending along substantially the entire length of the roll and around the circumference of the roll through an arc of less than 360, rotating said rolls in synchronism at a certain speed about their respective axes, revolving the rolls at a certain speed as a unit about the central axis of the tubing, varying one of said speeds whereby those portions of the working surfaces in contact with the tubing remain stationary with respect to the tubing, and advancing the tubing in increments through the rolls.

2. A process for reducing tubing or the like comprising the steps of passing the tube centrally between a plurality of tapered rolls revolving as a unit at a constant speed about the central axis of the tubing, each having a spiral working surface extending along substantially the entire length of the roll and around the circumference of the roll through an arc of less than 360; rotating the work rolls in synchronism about their respective axes while varying the rotational speed thereof whereby those portions of the working surfaces in contact with the tubing remain stationary with respect to the tubing; and advancing the tubing in increments through the rolls.

3. A process for reducing tubing and the like comprising the steps of passing the tubing centrally between a plurality of tapered rolls revolving as a unit at a constant speed about the central axis of the tubing, each having a spiral working surface extending along substantially the entire length of the rolls and around the circumference of the rolls through an are less than 360; rotating the rolls in synchronism about their respective axes while varying the rotational speed thereof as a function of the diameter of the tubing and the area of contact between the working surfaces and the tubing; and advancing the tubing incrementally through the rolls.

4. A process for reducing tubing and the like comprising the steps of passing the tubing centrally between a plurality of tapered rolls rotating in synchronism about their respective axes and each having a spiral working surface extending along substantially the entire length of the roll and around the circumference of the roll through an arc of less than 360 to provide a break in the'working surface at the feed end of the rolls; and advancing the tubing centrally between the rolls only when the breaks in the working surfaces are adjacent to and in opposition with the tubing.

5. In apparatus for reducing tubing and the like, the combination comprising a housing supported for rotation about a central axis of said housing; tapered work rolls journaled within said housing for rotation about their longitudinal axes, said longitudinal axes being parallel with and equidistantly spaced from one another and said central axis, each of said work rolls having at least one spiral working surface extending along substantially the entire length thereof and around the circumference thereof through an arc of less than 360, said tapered work rolls being so disposed whereby they present gradually converging working surfaces for the reduction of a tube; first drive means for rotating said housing and said work rolls as a unit about said central axis; second drive means for rotating said work rolls in synchronism about said longitudinal axes independently of said first drive means; and means for varying the speed of one of said drive means whereby those portions of the spiral working surfaces in contact with the tube remain stationary relative to the outer surface of the tube.

6. In apparatus for reducing tubing and the like, the combination comprising a housing supported for rotation about a central axis of said housing; tapered work rolls journaled within said housing for rotation about their longitudinal axes, said longitudinal axes being parallel with and equidistantly spaced from one another and said central axis, each of said work rolls having at least one spiral working surface extending along substantially the entire length thereof and around the circumference thereof through an arc of less than 360, said tapered work rolls being so disposed whereby they present gradually converging working surfaces for the reduction of a tube; first drive means for rotating said housing and said work rolls as a unit at a constant speed about said central axis; second drive means for rotating said work rolls in synchronism about said longitudinal axes independently of said first drive means; and means for varying the speed of said second drive means whereby those portions of the working surfaces in contact with the tube remain stationary relative to the outer surface of the tube.

7. In apparatus for reducing tubing and the like, the combination comprising a housing supported for rotation about a central axis of said housing; tapered work rolls journaled within said housing for rotation about their longitudinal axes, said longitudinal axes being paral lel with and equidistantly spaced from one another and said central axis, each of said tapered work rolls having at least one spiral working surface extending along substantially the entire length thereof, said tapered work rolls being positioned whereby the working surfaces define a gradually converging pass for the reduction of a tube, each of said spiral working surfaces extending around the circumference of said tapered work rolls through an arc of less than 360 thereby providing an interruption in the working surface at the feed end of each tapered work roll; means for advancing said tube through said tapered work rolls only in the area of the interruptions in said working surfaces; first drive means for rotating said tapered work rolls in synchronism about a unit about the said central axis; second drive means for rotating said tapered with rolls in synchronism about said longitudinal axes and independently of said first drive means; and means for varying the speed of one of said drive means whereby those portions of the working surfaces in contact with said tube remain stationary relative to the outer surface of the tube.

8. In apparatus for reducing tubing and the like, the combination comprising a housing supported for rotation about a central axis of said housing; tapered work rolls journaled within said housing for rotation about their longitudinal axes, said longitudinal axes being parallel with and equidistantly spaced from one another and said central axis, each of said work rolls having at least one spiral working surface extending along substantially the entire length thereof and around the circumference thereof through an arc of less than 360, said tapered work rolls being so disposed whereby they present gradually converging working surfaces for the reduction of a tube; first drive means comprising an external gear means contiguous with the outer surface of said housing and extending around the circumference thereof, and driving gear means maintained in meshing relation with said external gear means for driving said housing and said tapered work rolls as a unit about said central axis; second drive means for rotating said tapered work rolls in synchronism about their longitudinal axes and independently of said first drive means; and means for varying the speed of one of said drive means whereby those portions of the working surfaces in contact with the tube remain stationary relative to the outer surface of the tube.

9. In apparatus for reducing tubing and the like, the combination comprising a housing supported for rotation about a central axis of said housing; tapered work rolls journaled within said housing for rotation about their longitudinal axes, said longitudinal axes being parallel with and equidistantly spaced from one another and said said central axis, each of said work rolls having at least one spiral working surface extending along substantially the entire length thereof and around the circumference thereof through an arc of less than 360", said tapered work rolls being so disposed whereby they present gradually converging working surfaces for the reduction of a tube; first drive means for rotating said housing and said work rolls as a unit about the said central axis; second drive means comprising ring gear means having internal and external gear teeth, planetary gear means secured to each of said tapered work rolls externally of said housing, said planetary gear means being maintained in meshing relation with the said internal gear teeth of said ring gear means whereby said tapered work rolls are rotated in synchronism about their longitudinal axes, and driving gear means maintained in meshing relation with said external gear teeth of said ring gear means; and means for varying the speed of one of said drive means whereby those portions of the working surfaces in contact with the tube remain stationary relative to the outer surface of the tube.

10. In apparatus for reducing tubing and the like, the combination comprising a housing supported for rotation about a central axis of said housing; tapered work rolls journaled within said housing for rotation about their longitudinal axes, said longitudinal axes being parallel with and equidistantly spaced from one another and said central axis, each of said work rolls having at least one spiral working surface extending along substantially the entire length thereof and around the circumference thereof through an arc of less than 360, said tapered work rolls being so disposed whereby they present gradually converging working surfaces for the reduction of a tube; first drive means comprising external gear means contiguous with the outer surface of said housing and extending around the circumference thereof, and first driving gear means maintained in meshing relation with said external gear means for driving said housing and said work rolls as a unit about said central axis; second drive means comprising ring gear means having internal and external gear teeth, planetary gear means, one each secured to each of the tapered work rolls externally of said housing,

said planetary gear means being maintained in meshing relation with said internal teeth of said ring gear means whereby said tapered work rolls are rotated in synchronism about their longitudinal axes, and second driving gear means maintained in meshing relation with said external gear teeth of said ring gear means; and means for varying the speed of one of said drive means whereby those portions of the working surfaces in contact with the tube remain stationary relative to the tube.

11. In apparatus for reducing tubing and the like, the combination comprising a housing supported for rotation about a central axis thereof; tapered work rolls journaled within said housing for rotation about their longitudinal axes, said longitudinal axes being parallel with and equidistantly spaced from one another and said central axis, each of said work rolls having at least one spiral working surface extending along substantially the entire length thereof and around the circumference thereof through an arc of less than 360, said tapered work rolls being so disposed whereby they present gradually converging radially opposed working surfaces for the reduction of tubing, gear means on said housing adapted to rotate said housing and said work rolls as a unit about said central axis; gear means rotatable about said central axis and adapted to rotate said work rolls in synchronism about their longitudinal axes; and drive means for rotating one of said gear means, the other of said gear means being freely rotatable about said central axis whereby those portions of the working surfaces in contact with the tubing remain stationary relative to the outer surface of the tubing.

12. In apparatus for reducing tubing and the like, the combination comprising tapered work rolls journaled within a housing for rotation about their longitudinal axes, said work rolls being equiangularly spaced about a central axis of said housing, said tapered work rolls having at least one spiral working surface extending along substantially the entire length thereof, said tapered work rolls being positioned whereby the working surfaces define a gradually converging pass for the reduction of a tube, each of said spiral working surfaces extending around the circumference of said tapered work rolls through an arc of less than 360 thereby having a break in the working surface; and means for feeding said tube centrally between said tapered work rolls only when said breaks in said working surfaces are in opposed relation and adjacent to the said tube.

13. In apparatus according to claim 12, said feeding means comprising carriage means frictionally engaged with said tube; means forming a projection on said carriage means; connecting means movable with respect to said carriage means; drive means for continuously advancing said connecting means towards said projection; and spring means interposed between said connecting means and said projection whereby the continuous advance of said connecting means will compress the spring means until said tube is free to advance.

References Cited by the Examiner UNITED STATES PATENTS 808,001 12/1905 Briede 72189 1,810,698 6/1931 Diescher 72421 1,890,803 12/1932 Coe 72421 2,017,387 10/1935 Bannister 72104 2,045,602 6/1936 Huntsman 72103 2,358,307 9/1944 Dewey 72104 3,025,816 3/1962 McCoy 72104 3,073,190 1/1963 Appel 72421 CHARLES W. LANHAM, Primary Examiner.

H. D. HOINKES, Assistant Examiner. 

1. A PROCESS FOR REDUCING TUBING OR THE LIKE COMPRISING THE STEPS OF PASSING THE TUBE CENTRALLY BETWEEN A PLURALITY OF TAPERED WORK ROLLS EACH HAVING A SPIRAL WORKING SURFACE EXTENDING ALONG SUBSTANTIALLY THE ENTIRE LENGTH OF THE ROLL AND AROUND THE CIRCUMFERENCE OF THE ROLL THROUGH AN ARC OF LESS THAN 360*, ROTATING SAID ROLLS IN SYNCHRONISM AT A CERTAIN SPEED ABOUT THEIR RESPECTIVE AXES, REVOLVING THE ROLLS AT A CERTAIN SPEED AS A UNIT ABOUT THE CENTRAL AXIS OF THE TUBING, VARYING ONE OF SAID SPEEDS WHEREBY THOSE PORTIONS OF THE WORKING SURFACES IN CONTACT WITH THE TUBING REMAIN STATIONARY WITH RESPECT TO THE TUBING, AND ADVANCING THE TUBING IN INCREMENTS THROUGH THE ROLLS. 